"""
分段函数求值
        3x - 5  (x > 1)
f(x) =  x + 2   (-1 <= x <= 1)
        5x + 3  (x < -1)
"""

x = float(input('x = '))
if x > 1:
    y = 3*x-5
elif x <=1:
    if x>=-1:
        y=x+2
    else:
        y=5*x+3
print('f(%.2f)=%.2f' % (x, y))
